BTopenworld has promised to refund its broadband customers after its billing system failed to charge users the new lower rate for the ISP's DSL service.

Earlier this month BTopenworld said it would cut the cost of its service to £29.99 a month following a cut in the wholesale price for DSL.

In an email to its consumers the ISP said: "We're delighted to tell you that we'll be reducing the monthly fee on your BTopenworld Broadband service from 1st April 2002.

"This means that your current monthly rental fee of £39.99 will be reduced to only £29.99.

"You don't have to do anything, as the reduction will be made automatically from your April bill onwards," it said.

However, two people have contacted The Register to say that BTopenworld has not automatically made the changes to their bill.

Both were shocked to find that according to statements sent out by BTopenworld they will be charged £39.99 a month for April.

At this stage it's not known how many people have been hit by the glitch.

BTopenworld admitted the cock-up and said that all those affected would receive a credit in their next bill.

"Our billing cycle runs from March and new prices which take effect as of April are not visible on this bill. All customers will receive a credit for the reduced rental price, which takes effect as of April 1, in their next bill," it said. ®